Dynamo-electric machine.



No. 666,849. Patented Jan. 29, I90I.-

E. JENNEY.

DYNAMO ELECTRIC IIACHINE.

(Application filed Kay 5, 1899.)

(No Model.) 2 Sheets Shaut l.

WITNESSES: INVENTOR- m0 EY- FIGJ No. 666,849. Patented Jan. 29, I90l. A. E. JENNEY. DYNAMO ELECTRIC MACHINE.

(Application filed m a, 1899.)

2 Sheots-$hoot 2.

(No 'llodal.)

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UNITED STATES PATENT OFFICE.

ARTHUR E. JENNEY, OF BOSTON, MASSACHUSETTS, 'ASSIGNOR TO THE I-IOLTZER OABOT ELECTRIC COMPANY, OF BROOKLINE, MASSACHU- SETTS;

DYNAMO-ELECTRIC MACHINE.

SPECIFICATION forming part of Letters Patent No. 666,849, dated January 29, 1961.

Application filed May 5, 1899. Serial No. 715,654. (No model.)

To all whom it may concern:

Be it known that I, ARTHUR E. JENNEY, a citizen of the United States of America, and a resident of Boston, in the county of Suffolk and State of Massachusetts, have invented a new and useful Improvement in Dynamos, of which thefollowing is a specification.

My invention relates to a dynamo adapted to be employed in operating electric telephone systems, while more particularly it is intended to remove the difficulty heretofore experienced in the operation of telephone-receivers. By the use of my invention the whistling or humming sound in the receivers is practically perfectly prevented.

The invention is shown in all its details in the accompanying drawings.

Figure 1 shows adynamo connected up with telephone-circuits. Figs. 2 and 3 are different views of one form of pole-pieces for the dynamo. Figs. 4 and 5 represent modified pole-pieces. Fig. 6 is an end view of a further modification in this direction. Fig. '7 is an end view of a still further modification. Fig. 8 shows an end view of another modification. Fig. 9 is a side elevation of the dynamo, showing especially the construction of the armature and commutator. Fig. 10 shows two curves, A showing the abruptness of the electromotive force resulting in currents generated by the usual dynamo, While B shows the nature of the curve with my dynamo. Fig. 11 is a plan of the armature with its winding, together with a projection of a section of one of the pole-pieces on its cylindrical face, in I order to show the relative positions and shapes in a plan view of the pole-piece and the armature-winding.

In the drawings, a represents the polepieces of the dynamo. There may be four pole-pieces, as in Figs. 1 and 9, or there may be six pole-pieces, or the number may be still varied, as in other dynamos, as the number of pole-pieces has practically nothing to do with the invention.

By reference especially to Fig. 11 it will be noticed that the pole-piece represented by the sectional portion a is so shaped that the horns b are narrower than the central portion of the pole-piece and that the thickness of the polepiece between the central portion and the horns b gradually decreases, the eftect being that during the rotation of the armature the conductors 9 do not, as in the ordinary forms of dynamos, approach or recede from the magnetic lines of force abruptly. The field of force at the horns is at a minimum and gradually varies to the central portion of the polepiece, with the consequent prevention of sudden or abrupt variations in the electromotive force of the current generated, and consequently, as discovered by me, no whistling is produced in the telephone receivers. The construction of the invention in this respect may be varied without departing from the spirit of the invention.

In Figs. 2 and 3 the core of the field-magnet is represented at d. The pole-piece a is made separately and then secured to a projection '6, extending from the core 01. The pole-piece is, as usual, curved on its face, with substantially'the same radius as that of the armature,and the horns, as explained with reference to Fig. 11, are pointed or tapered in a direction measured from the central portion of the pole to its horns.

Figs. 4 and 5 are side and end views of the shape of a pole-piece having rounded sides and ends like that in Fig. 7, butthe pole-piece is somewhat more rounded at the ends.

In Fig. 6 the shape of the pole-piece is represented as being oval, the longer axis being that between the horns. The pole-piece may of course be, when of any shape, eithenmade separately and attached to the core orit may be made in a single piece with the core.

In Fig. 7 the pole-piece a is somewhat of the same shape as in Figs. 2 and 3, except that the horns at the pointed ends are rounded.

An important modification is shown in Fig. 8, where one horn is pointed, whereas the opposite corresponding portion acting as the horn is not tapered or pointed.

In Fig. 9 is shown especially the armature, which has a smooth surface f, upon which are the windings g. It is important in the construction of the invention that attention should be paid to the armature in this respect, for investigation has shown that much of the whistling in the receiver is due to notches or holes or other irregularities in the iron core of the armature. As shown in Fig. 9, the surface of the armature f, upon which the conductors 9 rest, is continuous throughout the whole circumference in order to be free from projections, teeth, holes, and the like, such as all kinds of interruptions and breaks.

In the practical construction of the dynamo it is of advantage to multiply as far as possible the number of commutator-sections which are shown very numerous in the drawings, and they should be as numerous as the condition of the case will permit.

The dynamo is shown connected up in circnit with telephone apparatus in Fig. 1. It is important to notice that there are three important features involved. The shape of the pole-pieces, as hereinbefore explained, maybe considered from a broad point of view as an important feature of the invention by itself or in combination with the other important features, and what I claim to be novel is particularly set forth in the accompanying claims; but Fig. 1 shows the preferable manner in which the invention should he used in practice. A secondary battery it is included in circuit between the main lines 2' and j. Beyond the main lines the telephone apparatus is included in circuit in the usual manner, q being the transmitter, the inductioncoil, and Z the receiver.

My invention may be used for all the purposes for which it is adapted and in all the different ways that may be desired, and what is shown in Fig. l is not in any way to be con sidered as limiting me to any particular manner of using the invention.

The operation of the invention in so far as I am able to give the reasons for its operation is as follows, and calculation and investigation have satisfied me that the results claimed hereinbefore are satisfactorily secured: Assuming that the magnetic lines of force passing from the pole at to the armaturecoils are equally distributed over each unit of area of the face of the pole a, then the number cut by any given armature-conductor will be directly proportional to the width of the pole-face directly above it, and hence in passing, for example, from the center to the extremity of the pole-face the number of such lines will gradually decrease from a maximum at the center to approximately zero or a minimum at the point. The electromotive force induced in the conductor being strictly proportional to the number of lines cut by the same per unit of time, this electromoti ve force will therefore decrease gradually from about maximum to about zero, and

there will be no sudden jump such as happens when the pole-piece ends abruptly, as in the ordinary type of machine.

Finally as a feature of the construction I employ in my dynamo a comparatively weak magnetic field. Furthermore, in the construction of the invention iron-clad armatures should not be employed, nor, as already stated, slotted armatures. In the ease of toothed armatures, for example, I believe that the cause of the whistling arises from the magnetism jumping suddenly from one tooth to the next on leaving the field. This difficulty is overcome by the employment of a smooth-face armature-core, as hereinbefore explained.

Although I have indicated that the general manner of using the invention is to combine the dynamo with a storage battery in circuit therewith, yet by the employment of a chokecoil in circuit with a dynamo the latter may be used directly to produce the proper current on a telephone-line than without the use of any secondary batteries alone. The type of dynamo hereinbefore described is a contin nous-current dynamo.

I claim as my invention- 1. In adynamo the combination of a polepiece of a predetermined width at its central portion and tapered to approximately a point in a direction substantially parallel to the circumference of the armature of said dynamo, with an armature whose conductors are so arranged that a projection of the pole-piece upon the armature-conductors covers a less and less length of said conductors from the central portion of the pole-piece to the horns thereof, substantially as and for the purpose described.

2. In a dynamo,the combination of an arma ture-core, having the surface thereof next to the pole-pieces continuously cylindrical and free from projections, holes, teeth and the like, arm attire-conductors at or upon said surface, and parallel to the axis of said cylinder, and pole-pieces each of. which is of a predetermined width at its central portion and tapered to approximately a point in a direction substantially parallel to the circumference of the armature of said dynamo in such a manner that the projection of the pole-piece upon the armature-00nductors covers a less and less length of said conductors from the central portion of the pole-piece to the horns thereof.

3. In a dynamo, the combination of armature-conductors, a pole-piece of a predetermined width at its central portion, and tapered gradually to the end of one or both of the horns or tips thereof, in such a manner that a projection of the pole-piece upon the armatureconductors, covers a less and less length of said conductors from the central portion of the ipole-piece to the end of the tapered horn or tip thereof, and an armaturelength of said conductors from the central core whose whole surface, adapted to move portion to the horn or horns thereof. IO past the pole-pieces, is continuous and free In testimony whereof I have hereunto subfrom projections, holes, teethand the like. scribed my name this 25th day of April, 1899.

5 4;. Inadynamo,the combination ofan arma- ARTHUR E. JENNEY. [L. 5.]

tnre, conductors thereon, and a pole-piece so Witnesses: shaped that a projection thereof upon the T. W. NESS',

armature-conductors covers a less and less IRA A. FOSTER; 

